The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 2002-031895 filed Feb. 8, 2002.
1. Field of the Invention
The present invention relates to a vibration preventing device that prevents a vibration of a member and a blur correcting device that corrects an image blur in a photographing apparatus or the like provided with the vibration preventing device.
2. Description of the Related Art
In a blur correcting device, a blur correction optical system which corrects an image blur by moving along a direction substantially perpendicular to the optical axis is provided at a movable member so that the blur correction optical system is made to move together with the movable member. In the device, smoother drive control can be achieved as the drive resistance of the movable member is lowered and, accordingly, Japanese Laid-Open Patent Publication No. H 9-80583 discloses a structure in which the movable member is supported by an elastic support member (wire).
In addition, such a device includes a locking member that restricts the movement range of the movable member to a locking range which is narrower than the blur correction control range of a blur correction drive unit when no blur correction control is implemented and thus, the position of the blur correction optical system is stabilized.
However, a certain degree of dimensional tolerance and the like must be assured in the device in the related art described above and, for this reason, a gap is formed between the movable member and the locking member. As a result, a slight mechanical vibration (e.g., a shock caused by the mirror, the shutter or the like in a single lens reflex camera) or the like in the photographing apparatus is transmitted and the movable member is allowed to move within the locking range even while it is in a locked state.
The movable member does not move readily due to a mechanical vibration or the like in the photographing apparatus in the related art during a photographing operation performed with the lens set horizontally, since the movable member moves downward under its own weight to come into contact with the locking member in this state. However, the movable member and the locking member do not come into contact with each other and thus, the movable member is caused to move readily by a mechanical vibration or the like during a photographing operation performed with the lens turned upward or downward.
In addition, there is a problem in that if the drive resistance of the movable member is lowered as described earlier in order to achieve better control on the movable member, the movable member becomes even more prone to move in response to a slight mechanical vibration or the like.
Since the blur correction optical system moves as well when the movable member moves as described above, the image quality becomes poor.
The present invention provides a vibration preventing device that enables a reliable lock of the movable member and a blur correcting device that employs this vibration preventing device.
A vibration preventing device according to the present invention comprises: a movable member capable of moving within a predetermined plane; a drive unit that drives the movable member to move within the predetermined plane; a restricting member that is set to either a first position at which movement of the movable member within the predetermined plane is physically enabled or to a second position at which the movement of the movable member within the predetermined plane is restricted; and a pressure member that further prevents the movement of the movable member within the predetermined plane by applying pressure to the movable member along a direction substantially perpendicular to the predetermined plane while the movement of the movable member within the predetermined plane is restricted by the restricting member.
In this vibration preventing device, it is preferable that the pressure member is constituted of at least two elongated leaf springs, and that longitudinal directions of the two leaf springs are set along different directions from each other.
It is also preferable that the pressure member is constituted of a single leaf spring member; and the leaf spring member comprises a contact portion that comes into contact with the movable member, a first arm portion having one end thereof fixed to the restricting member and another end thereof connected to the contact portion, that functions as a leaf spring, and a second arm portion having one end thereof fixed to the restricting member and another end thereof connected to the contact portion, that functions as a leaf spring and is set in a direction extending substantially perpendicular to the first arm portion.
It is also preferable that the restricting member is set to the first position or the second position as the restricting member itself moves; and the pressure member is fixed to the restricting member, is caused to move as the restricting member moves, applies pressure to the movable member when the restricting member is set at the second position, and releases the pressure to the movable member when the restricting member is set at the first position.
A blur correction optical system may be further provided that corrects an image blur by moving along a direction extending substantially perpendicular to an optical axis, and it is preferable that the blur correction optical system is mounted at the movable member and is driven by the drive unit so as to move along the direction extending substantially perpendicular to the optical axis; the restricting member allows movement of the blur correction optical system when set at the first position and restricts the movement of the blur correction optical system when set at the second position; and the pressure member further prevents the movement of the blur correction optical system along the direction extending substantially perpendicular to the optical axis by applying pressure to the movable member along the optical axis while the movement of the blur correction optical system is restricted by the restricting member.
A blur correcting device according to the present invention comprises: a blur correction optical system that corrects an image blur by moving along a direction extending substantially perpendicular to an optical axis; a movable member that includes the blur correction optical system and moves together with the blur correction optical system; a blur correction drive unit that drives the movable member; and a pressure member that applies pressure to the movable member in a direction extending substantially along the optical axis of the blur correction optical system, and switches between a state in which the pressure is applied to the movable member and a state in which no pressure is applied to the movable member by moving within a plane substantially perpendicular to the optical axis.
In this blur correcting device, a locking member may be further provided that is capable of moving between a locking position at which a movement range of the movable member is restricted to a locking range narrower than a blur correction control range of the blur correction drive unit and a lock-release position at which the movement of the movable member is not restricted within the locking range, and it is preferable that the pressure member applies the pressure to the movable member when the locking member is at the locking position and does not apply any pressure to the movable member when the locking member is at the lock-release position. In this structure, it is preferable that the pressure member is fixed to the locking member and moves together as the locking member moves; and the movable member includes a pressure receiving portion that comes in contact with the pressure member when the locking member is at the locking position and is not in contact with the pressure member when the locking member is at the lock-release position. It is preferable that the pressure member is constituted of a single leaf spring member; and the leaf spring member includes a contact portion that comes into contact with the movable member, a first arm portion having one end thereof fixed to the locking member and another end thereof connected to the contact portion, which functions as a leaf spring, and a second arm portion having one end thereof fixed to the locking member and another end thereof connected to the contact portion, which functions as a leaf spring and is set in a direction extending substantially perpendicular to the first arm portion.
It is also preferable that the movable member is supported by a plurality of wire members; and the pressure member applies the pressure to the movable member in a direction along which the wire members are stretched.
It is also preferable that the movable member is supported by a plurality of sliding portions or a plurality of balls; and the pressure member applies the pressure to the movable member in a direction along which the pressure is also applied to the sliding portions or the balls.
It is also preferable that the pressure member achieves a degree of rigidity high enough to ensure that substantially no deformation is caused within the plane substantially perpendicular to the optical axis by a force resulting from friction occurring at a contact area where the pressure member comes into contact with the movable member.
The pressure member may includes at least two substantially strip shaped leaf springs; and longitudinal directions of the leaf springs constituting the pressure member are set along directions extending substantially perpendicular to each other.
In another aspect of the blur correcting device according to the present invention, it comprises: a blur correction optical system that corrects an image blur by moving along a direction extending substantially perpendicular to an optical axis; a movable member that includes the blur correction optical system and moves together with the blur correction optical system; a restricting member having a restricting portion for restricting movement of the blur correction optical system along the direction extending substantially perpendicular to the optical axis, that is capable of moving between a restricting position at which the movement of the blur correction optical system is restricted and a non-restricting position at which the movement is not restricted; and a contact member provided at one of the movable member and the restricting member, that assumes a position at which the contact member comes into contact with the movable member or the restricting member where the contact member is not provided when the restricting member moves to the restricting position and assumes a position at which the contact is cleared when the restricting member moves to the non-restricting position.
A lens barrel according to the present invention comprises a vibration preventing device or a blur correcting device described above.
A camera according to the present invention comprises a vibration preventing device or a blur correcting device described above.